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Peatland Diversity and Carbon Dynamics

Date post: 20-Oct-2014
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The winning talk at the Macaulay Land Use Research Institute's annual Student Seminar Day, given by Mike Whitfield as part of his PhD research.
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Peatland Diversity and Carbon Dynamics Mike Whitfield Nick Ostle, Richard Bardgett, Rebekka Artz [email protected] | www.mikewhitfield.co.uk
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Page 1: Peatland Diversity and Carbon Dynamics

Peatland Diversity and Carbon Dynamics

Peatland Diversity and Carbon Dynamics

Mike WhitfieldNick Ostle, Richard Bardgett, Rebekka [email protected] | www.mikewhitfield.co.uk

Page 2: Peatland Diversity and Carbon Dynamics

• Background:Peatlands and climate changeAbove- and below-ground links

• Research:– Plant and soil diversity– Peatland carbon stocks– Greenhouse gas emissions (CO2, CH4, N2O)

• Conclusions

Page 3: Peatland Diversity and Carbon Dynamics

• Globally, peatlands constitute 25 – 30% of the soil carbon pool

• Climate warming is projected to be greatest over high northern latitudes, coincidental with a high proportion of the world’s peatlands

• Roughly 8% of UK is covered with blanket peat moorland

Introduction: Peatlands

Map data: Jones et al. 2005: Estimating organic carbon in the soils of Europe for policy support. DOI: 10.1111/j.1365-2389.2005.00728.x

Page 4: Peatland Diversity and Carbon Dynamics

• Globally, peatlands constitute 25 – 30% of the soil carbon pool

• Climate warming is projected to be greatest over high northern latitudes, coincidental with a high proportion of the world’s peatlands

• Roughly 8% of UK is covered with blanket peat moorland

Introduction: Peatlands

Page 5: Peatland Diversity and Carbon Dynamics

• To a depth of 1m, UK peatlands contain 1357Mt C, nearly half of which is in Scotland

• A loss of 12% of the UK peatland area = total annual UK human GHG emissions

(Bradley et al. 2005; Smith et al. 2010)

Page 6: Peatland Diversity and Carbon Dynamics

• Estimates of global soil organic carbon stocks range between 700 – 2946 x 1012 kg

• Need reliable estimates based on upscaling processes from small to larger scales to resolve uncertainty.

• ‘Bucket and slab’ peatland models

• What about the biological functioning?

Introduction: Climate-Carbon Feedback Uncertainty

Page 7: Peatland Diversity and Carbon Dynamics

• Growing evidence of feedbacks between the biosphere and global biogeochemical cycles.

• Plant-soil interactions lie at the heart of these feedbacks.

• Climate change and land use are powerful drivers of change in plant diversity.

• What will the implications be?

Introduction: Linking Plant and Soil Biodiversity

Pendall et al. 2008

Page 8: Peatland Diversity and Carbon Dynamics

Main Questions

• Are there any relationships between plant diversity-abundance and microbial community structure at the landscape scale?

• Can these relationships be used to predict ecosystem scale greenhouse gas emissions?

• How little do I need to know about biodiversity to predict ecosystem C cycling and GHG emissions?

Page 9: Peatland Diversity and Carbon Dynamics

• Area: 1146 ha

• Altitudinal range: 535 – 848m

• 90% blanket peat

Field Site: Trout Beck, Moor House, north Pennines

Page 10: Peatland Diversity and Carbon Dynamics

• Survey of peatland condition (plant-soil diversity and carbon stocks)

• Measurement of peatland GHG function

• Statistical analyses and spatial modelling of both (LiDAR, image classification and geostatistics (e.g. regression kriging)

…to predict carbon dynamics and greenhouse gas fluxes at the ecosystem scale

Upscaling Peatland Carbon Dynamics

Page 11: Peatland Diversity and Carbon Dynamics

Peat Bog Landforms

Page 12: Peatland Diversity and Carbon Dynamics

Peat Bog Landforms

Page 13: Peatland Diversity and Carbon Dynamics

Methodology: soil-sampling

•Soil C and N

•PLFA

•T-RFLP

•Large-scale vegetation survey (419 quadrats)

• Species presence and percentage cover

• Vegetation height at 3 in-plot locations

• Habitat context

• Topography: aspect, slope

• Peat depth

Page 14: Peatland Diversity and Carbon Dynamics

Methodology: soil-sampling

Spatial distribution of soil sampling

Coring locations randomly selected based on membership of landform (OM, EA, GU) and depth (0-100, 100-200, 200-300cm) categories

Microbial community sampling:

Three depths within each core

Based on mean water table conditions derived from published and unpublished data

0-5cm: Acrotelm

15-20cm: Mesotelm

75-80cm: Catotelm

Page 15: Peatland Diversity and Carbon Dynamics

Landscape Survey Results

Open moorland: 52%

Eroded areas: 11%

Gullies: 12%

Page 16: Peatland Diversity and Carbon Dynamics

Landscape Survey Results

Open moorland: 52%

Eroded areas: 11%

Gullies: 12%

Page 17: Peatland Diversity and Carbon Dynamics

Above-ground: Vegetation Composition

Page 18: Peatland Diversity and Carbon Dynamics

Below-ground: Peat Depths

• Deepest peat under open moorland

• Kruskal-Wallis test indicates significant differences between landform types (p < 0.001)

Page 19: Peatland Diversity and Carbon Dynamics

Below-ground: Carbon Stocks

Significantly lower CN ratio in gullies (ANOVA, f = 34.6, p <0.001)

Higher C content in gullies(Kruskal-Wallis, p <0.001)

Page 20: Peatland Diversity and Carbon Dynamics

• Significant differences between landforms for Actinobacterial and Total PLFA (Kruskal-Wallis tests: p <0.001 and p = 0.005 respectively)

• Perhaps reflecting lack of plant inputs on bare peat in eroding areas…

Below-ground: Microbial community

Page 21: Peatland Diversity and Carbon Dynamics

Below-ground: Microbial community

Significant difference in vegetation cover between landforms (ANOVA, p <0.001)a a

b

Page 22: Peatland Diversity and Carbon Dynamics

Greenhouse Gas Fluxes: Experimental Design

• What are the differences in greenhouse gas fluxes between landforms?

• 36 chambers on fixed plots– 3 landforms– 3 depth classes– 4 replicates

CO2

N2O

CH4

Page 23: Peatland Diversity and Carbon Dynamics

• Monthly sampling using static dome chambers, Infra-Red Gas Analysers (IRGAs) and gas chromatography

• Continuous landform hydrology and temperature measured using automated dip wells

• Seasonal sampling for C and N, microbial PLFA and T-RFLP

• May 2010 to June 2011

Greenhouse Gas Fluxes: Experimental Design

Image: Sue Ward

Page 24: Peatland Diversity and Carbon Dynamics

Greenhouse Gas Fluxes: Preliminary Results

Page 25: Peatland Diversity and Carbon Dynamics

Upscaling Peatland Carbon Dynamics to the Ecosystem Scale

Page 26: Peatland Diversity and Carbon Dynamics

Conclusions so far…

• Are there any relationships between plant diversity-abundance and microbial community structure at the landscape scale?o Differences in the composition of Plant Functional Types between landforms

are clearly visibleo Eroding areas have lower microbial biomass, which may be a reflection of

lower vegetation cover on bare peat

• Are there differences in below-ground carbon dynamics between landform types?o Gullies have a greater carbon content, and a lower CN ratio

• Can these relationships be used to predict ecosystem scale greenhouse gas emissions?

• How little do I need to know about biodiversity to predict ecosystem C cycling and GHG emissions?

Page 27: Peatland Diversity and Carbon Dynamics

Acknowledgements

This talk can be downloaded from www.mikewhitfield.co.uk

• Many thanks to:Catherine Turner, Sean Case, Simon Oakley, Susan Ward, Sergio Menendez Villanueva, Harriett Rea, Paula Reimer, David Beilman and Nicola Thompson

Mike Whitfield is supported by a Natural Environment Research Council CASE studentship.


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